Question

please answer both:)

2. In a recent survey, we are 95% confident the population percentage of all adults that believe in UFO's is between 18.25% and 20.75%. a. Determine the Best point Estimate. b. Determine the Margin of Error. 3. In a March 2010 poll of 1600 American adults, 1088 described themselves as "totally happy" (this category included both very happy" or "somewhat happy” responses) Use STATCRUNCH to construct a 95% confidence interval for the proportion of American adults who describe themselves as "totally happy." a. Best Point Estimate b. Margin of Error for a 95% confidence level. c. Construct the 95% confidence interval for the proportion of American adults who describe themselves as "totally happy". Statement: (Round to 4 decimal places.) d. Can we safely say that more than half of American adults describe themselves as "totally happy"?

Answer 1

1)

Given interval is (18.25, 20.75)

That is lower limit = 18.25

Upper limit = 20.75

A)

Best point estimate = (upper limit + lower limit)/2

Best point estimate = 19.5%

B)

Margin of error is given by

(Upper limit - Lower limit)/2 = 1.25%